I would say go for it. I have a 30 gallon on a dresser, that has a drawer right under the top piece same as yours. I have had it on there for a year now and no problems. Yours looks solid enough.
Yeah i think you would really be fine, I also have a 10 gallon sitting on a little night stand my father built in high school, and the legs are just little pegs at an angle. Hope your stand turns out great, good luck. It's also nice of your grandpa.
ill have to keep it up there anyway. i wont be able to drain three tanks and move them. i dont even know how ill put water in the 20 gallon. (i sprained me ankle) so everybody will this be ok for about a month?